There is increasing evidence that processing and transport controls play a major role in adenovirus 2 gene expression at early times after infection. The exact nature of the RNA's synthesized, their rates of synthesis, and the arrangement on the genome of the transcription units coding for these RNA's is not known at this time. The experiments outlined in this proposal are designed to characterize early viral gene expression with an emphasis on defining processes in viral RNA metabolism where regulatory controls may act effectively. In addition, attempt, to define the function of these gene products are also outlined. The principal technique to be utilized is the exhaustive hybridization of pulse-labeled viral RNA to Ad2 DNA fragments. The experiments are designed to quantitate and characterize the RNA synthesized from various regions of the DNA. In some experiments UV-irradation is used to alter gene expression. This alteration of Ad2 genomes with increasing UV dosage is used to define the number and size of the transcription units. The experimental results can then be used to construct a map of the Ad2 transcription units that are expressed at early times. In addition the mode of generation of viral complementary symmetrical transcripts will be determined by these techniques, and the role of early viral gene expression on viral DNA synthesis, T-Ag expression, host DNA and protein synthesis, and tumorigenicity will also be investigated. These studies will better characterize the early events during a productive infection and help define some of the early gene functions.